Audio Merge KTBK-1B Altec 9069B Filter

Based on the Altec 9069B High Pass Filter as used by King Tubby (and many others) at King Tubbys Studio in Waterhouse Jamaica and which was ultimately installed in Tubby's MCI desk, known infamously as King Tubby's Big Knob. The Audio Merge KTBK-1B is beautifully designed and engineered to the highest standard for your dubbing pleasure.

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PRICE: £525.00 EX VAT (£630.00 INC VAT)



This is a joy – based on the Altec 9069B High Pass Filter as used by King Tubby (and many others) at Tubby’s studio – installed in Tubby’s MCI desk and fitted with a big red control knob, hence the sobriquet King Tubby’s Big Knob.


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Demos below

The Audio Merge KTBK is beautifully designed and engineered to the highest standard. To get the Tubby’s sound, use it before an echo or reverb send or mix the filtered signal in parallel for authentic manual phasing effects.

By sweeping and blending the filtered signal with the dry creates distinctive (and very addictive) phasing effects: especially effective when used on a send to external effect (tape echo, spring reverb etc).

As with all passive switchable filters, there is an element of clicking when switching between bands, especially with more low frequency material (you can hear it in Tubby’s productions). With a little experimentation, you quickly get a feel for it, after which it becomes extremely addictive!

Based on the Altec 9069B high pass filter which was a key element in King Tubby’s sound. Tubby built his Altec into the MCI console in his Waterhouse studio with a big red control knob, hence the name.


  • Passive LC Filter
  • Replica of Altec 9069B aka Big Knob
  • 3rd-Order High Pass Filter
  • 10 Stepped Cut-off Frequencies
  • Mode Selector and a Resonance Leveler
  • 3 Modes: BELL, 600Ω, NOTCH
  • Designed by Reverse Engineering techniques
  • Customized Multi-Tap Inductor
  • Robust DSP Validation
  • Fully Analog Signal Path
  • Handbuilt with Love in BCN

The KTBK filter is a very precise replica of the Altec 9069B adapted for the modern studio with new controls for impedance matching and resonance. It was designed through Reverse Engineering techniques and validated with DSP to achieve the most accurate cutoffs utilising a customized multi-tap coil.

Tweak the Big Knob to get different tones, textures and an unrivalled sound effect. Allows to remove rumble noise, the parasitic frequencies and muddy sound effect in order to reducing the masking effect and achiving a clear sound. The KTBK Variable Passive High Pass Filter has stepped frequency selection with ten unequally spaced cut-offs offering a crossover type action – 70, 100, 150, 250, 500, 1k, 2k, 3k, 5k and 7.5k. A need when it is required an accurate control of the sound tone.

Passive filters are very sensitive to the impedance matching. Originally, the Altec 9069B was designed to perform with a 600Ω impedance transfer standard and currently modern audio equipments require other values. Our unit includes a mode control switch to be adapted to any equipment, allows to reproduce the original HPF response, or to generate a resonance bell over the cut-off frequency.

Sweep and layer your sounds with the KTBK filter to get unmatched sound signature. Perfect gear to create a dynamic mix with LO-FI tones! The digitalization has changed the way to record, produce and process music. It is time to explore new ways, taking the best of analog and digital domain.

The assembly and subsequent validation of each unit is manually done in our workshop, sited in Barcelona. The multi-tap inductor is a custom-designed element based on various frequency response and phase distortion analyses using different cores and coil winding techniques, in order to get the most accurate cut-off frequencies. The customized stepped rotary switch offers a very smoothed rotation resistance to guarantee the creative freedom during the performance. High quality ELMA rotary switch with proven solvency in the world of professional audio equipment.

Passive filters are very sensitive to the impedance matching. Originally, the Altec 9069B was designed to perform with a 600Ω impedance transfer standard but currently audio equipments require other values. Our unit includes a mode control switch to be adapted to any equipment, allows to reproduce the original HPF response, or to generate a resonance bell over the cut-off frequency or a variable notch filter, we call it VARI-NOTCH because the attenuation level increases with the frequency.


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For sales in UK the price will include 20% VAT. Buyers elsewhere may incur VAT or other local taxes on import.

Featured Videos

Dub Mixing With the KTBK

Soul Sweep

Flying Cymbals


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